CE206 Lab3 - Fitts Law PDF

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CE206 – HCI & Visualization Autumn 2015 LAB 3 – Fitts’s Law The objective of this Lab is to understand Fitts’s Law and complete some calculations that will lead to improved design. All files for this lab are to be downloaded from Moodle: moodle.essex.ac/course/view.php?id=3649 We...

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CE206 – HCI & Visualization Autumn 2015

LAB 3 – Fitts’s Law The objective of this Lab is to understand Fitts’s Law and complete some calculations that will lead to improved design. All files for this lab are to be downloaded from Moodle: https://moodle.essex.ac.uk/course/view.php?id=3649 We can use Fitts's law to calculate how to minimize the delay between a user’s intention and clicking on a desired object (be it a menu item or a hyperlink). A reminder of Fitts’s Law:

where: T (or MT) is the average time taken to complete the movement (movement time). a represents the start/stop time of the device (intercept) – use 0.25s b stands for the inherent speed of the device (slope) – use 0.125s D is the distance from the starting point to the centre of the target W is the width of the target measured along the axis of motion

Step 1: Measure up Download and open the file called Lab3 - Fitts Law.ppt from the module homepage. Get yourself a measuring tape or ruler (available in the lab) and measure D (the distance from the centre of the page, marked with a red dot, to the centre of the target) and W (the width of the target along the axis of motion) for all the highlighted targets in the file. Put these measurements in a table.

CE206 – Autumn 2015

Lab 3

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Step 2: Calculate Fitts’s Law analysis Using your D and W measurements calculate the Mt for each highlighted target. For example, if you measured D as 5.2cm and W as 0.3cm you would calculate Mt as: Mt = 0.25 + (0.125 * log2(1 + (5.2 / 0.3)) = 0.7745s Add these calculations to the table. Hint: You can use Google to do the calculation of log2 by using the command lg()

Step 3: Change the design Go back to the Lab3 - Fitts Law.ppt file and add or edit the highlighted areas so as to improve the performance of the design without damaging the page’s functionality and quality of appearance (e.g., do not untidily clump everything together just to reduce D or S). For example, you may wish to increase the size of the top menu links to make the clickable area (and hence W) larger.

Step 4: Recalculate Fitts’s Law analysis Recalculate the Mt for the areas you changed and also for any new areas you have added.

CE206 – Autumn 2015

Lab 3

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